This invention relates to an internal combustion engine cylinder block and more particularly to an improved lightweight, compact, high strength cylinder block for engines.
It is well known that there is a great desire to improve the performance of engines by reducing their weight and size without sacrificing engine performance or durability. Obviously, this is an understandable goal, but one which is not always easy to achieve.
With most engines, the cylinder block performs a number of functions in addition to merely defining the cylinder bores in which the pistons reciprocate. Generally, the engine's cylinder block is formed with a cooling jacket which surrounds the cylinder bores and which also provides communication between the cooling jackets of the cylinder block and other portions of the engine, such as the cylinder head and, at times, manifolds.
Furthermore, when overhead valve arrangements are employed, the cylinder block must provide a passage for lubricant to return to the crankcase chamber from the cylinder head valve chamber. Also, it is desirable to provide ventilating air passages through which crankcase ventilating gases may pass to the valve chamber of the cylinder head for possible induction into the engine combustion chambers to reduce the emission of unburned hydrocarbons to the atmosphere.
In addition to these functions, the cylinder block generally forms a bell housing which at least partially encircles the flywheel at one end of the engine. Generally, the flywheel has a larger diameter than the transverse dimension of the cylinder block and hence, this bell housing portion is formed as an enlargement at one end of the cylinder block. This may provide a difficult shape to cast or otherwise form, and may also add unnecessarily to the overall weight and bulk of the cylinder block.
Finally, the cylinder block normally forms at least a portion of the bearing surfaces for the crankshaft. Therefore, it should be readily apparent that the cylinder block performs a number of functions in addition to forming the cylinder bore. Thus, the prior art type cylinder blocks have been rather massive in size and weight.
It is, therefore, a principle object of this invention to provide an improved, lightweight, compact cylinder block for an internal combustion engine. It is a further object of this invention to provide an engine cylinder block that will provide all of the functions normally served by a cylinder block and yet in a more compact and lighter weight arrangement.